The present invention relates generally to reducing noise in data, and more particularly to reducing noise in a spectroscopy data, such as spectra obtained from a mass spectrometer.
In a spectrometer, a data signal typically includes a useful signal component and a noise component. The “useful signal” is typically the data of interest. The “noise” can be characterized as any component not part of the signal of interest. One goal of any spectrometer is to be able to differentiate between the “signal” and the “noise” so that the signal can be qualified as “real” and useable. However, this goal can be hard to achieve as the noise can also hide important real signals.
For example, FIG. 1A shows a chromatogram 100 for a typical ion extraction of a particular compound where the signal and the noise are measured. FIG. 1B shows a chromatogram 150 having a magnified view of chromatogram 100. The noise 120 is shown with a bracket and two of the signals 110 are shown with arrows. FIG. 1B shows that the noise levels are an order of magnitude less than these two signals 110; however, the noise levels are still comparable to other useful signals. Also, given the size of the noise, it is possible that signals are hidden within the noise. Thus, if an atomic or molecular ion makes up a small percentage of the fragments of a compound, its existence could be lost and the true make-up of the compound could be lost.
It is clear that a spectrometer performs better if it can better differentiate between signal and noise. One measure of the performance of an instrument is a signal to noise (S/N) ratio, where a larger S/N means better performance. This ratio will improve if the signal is increased or if the noise is decreased. A greater S/N ratio allows better differentiation between signals and the noise, thus allowing a greater sensitivity for detecting ions. Other measures of performance are an improvement in the MDL (Minimum Detection Limit) or LLOD (Lower Level of Detection), where an improvement results in a lower level or limit.
Accordingly, it is desirable to provide systems and methods for improving performance of a spectrometer by reducing noise in spectral data.